Filter device

ABSTRACT

A filter device comprises a filter housing ( 2, 4 ) accommodating a filter element ( 16 ) which separates an unfiltered substance chamber ( 26 ) from a filtrate chamber ( 20 ) within the filter housing ( 2, 4 ). The filter element ( 16 ) is sealed against the filter housing ( 2, 4 ) by a sealing device ( 36, 40 ). The disclosed filter device is characterized in that the filter element ( 16 ) is mounted inside the filter housing ( 2, 4 ) using movable bearings ( 32, 38 ).

The invention concerns a filter device comprising a filter housing, which holds a filter element that separates an unfiltrate chamber from a filtrate chamber inside the filter housing, where the filter element is sealed against the filter housing by means of a sealing device.

Filter devices of this kind (DE 10 2007 046 208 A1) are prior art and are available in the most diverse designs, different dimensions, filter characteristics and other specifications and are used in many applications for the filtration of fluids of all kinds. When used to filter operating fluids in engineering equipment, for example hydraulic fluids, fuel or lubricants, cooling liquids and such like, the filter devices are often installed in locations where they are subjected to vibrational loads in operation. This is the case when filter devices are used in mobile machinery such as excavators, front-end loaders, mobile cranes, forklifts and such like. Vibrations that act on the filter element can cause the destabilization of the respective filter medium, which causes a reduction in filter performance.

In this respect it is the object of the invention to provide a filter device that is characterized by an increased resistance to reduced effectiveness caused by vibrations.

This object is met according to the invention by a filter device that exhibits the characteristics of claim 1 in its entirety.

According to the characterizing part of claim 1, one significant feature of the invention is that the filter element is supported inside the filter housing solely by way of floating bearings. The combination of partially moveable support means allows for a vibration-dampened retention of the filter element and thus an improvement in operational reliability of a filter device that is subjected to vibrational loads.

It is possible to achieve a particularly effective vibration damping effect through the support means if the bearings act mainly in vertical direction with respect to each other, where, when the device is in operation, a first floating bearing acts mainly in horizontal, radial direction and a second floating bearing acts in vertical, axial direction.

In a particularly advantageous manner the respective bearing may be provided with a sealing ring of the sealing device, by means of which the filter element is sealed against the filter housing.

Particularly favourable conditions concerning the damping of vibrations are obtained if the respective sealing ring that forms part of the bearing is elastically flexible and consists preferably of an elastomeric material.

In particularly advantageous exemplary embodiments the sealing ring that forms part of the first floating bearing is disposed between a connection point of the filter element and a head of the filter housing, where the sealing ring that forms part of the second floating bearing is disposed between said filter head and a filter bowl of the filter housing. Thus, in the overall connection between filter element and filter bowl of the housing, which is obtained through the floating bearing between the filter element and the filter housing head and through the fixed bearing between the filter housing head and the filter housing bowl, an elastomeric bearing element each is provided so that it is possible to achieve an effective vibration damping effect by the thus formed support.

In particularly advantageous exemplary embodiments the one end cap of the filter element, which forms the connection point, is provided with a support surface that overlaps the filter bowl, where said support surface compresses with increasing connection between filter head and filter bowl the bearing-sealing ring, which acts primarily in vertical direction, against a further support surface in such a way that said sealing ring widens in radial direction. Said elastomeric, compressed sealing ring thus forms a pre-tensioned damping element between the support surfaces of the fixed bearing.

In a particularly advantageous manner the arrangement may be such that the further support surface for the bearing-sealing ring that forms the second floating bearing is made as part of the filter bowl and that the one support surface forms a closed external circumference ring, which is attached via connecting webs to the other parts of the end cap and which is provided with a shoulder at the outer circumference above the second floating bearing. Said shoulder at the outer circumference ring of the end cap facilitates the compression of the sealing ring of the second floating bearing.

The sealing ring that forms part of the first floating bearing may be located in a circumferential groove of a cylindrical extension of the end cap, which delimits the connection point and may be brought in contact with a cylindrical connection part of the filter head. Thus said floating bearing forms simultaneously a seal of the fluid passage between the connection point of the end cap and the internal cavity of the filter element into which the cylindrical extension protrudes and which forms, for example, the unfiltrate side in the filtering process.

To achieve particularly good damping characteristics, the diameter of the sealing ring that co-forms the first floating bearing is preferably smaller than the diameter of the sealing ring that co-forms the second floating bearing, where both bearings are located at a distance from each other in axial direction so that the filter element is supported essentially free of vibrations inside the filter housing.

According to claim 11 an object of the invention is also a filter element that is provided in particular for use in a filter device according to one of the claims 1 to 10, which comprises a filter material that extends between two end caps, where at least one of the end caps of the filter element is provided with receptacles for the components of two bearings, the working direction of which extends essentially vertical to each other.

The invention will now be explained in detail by way of an exemplary embodiment represented in the drawing. Shown are in:

FIG. 1 the upper part of an exemplary embodiment of the filter device according to the invention in perspective view and with different cross-sections in longitudinal direction;

FIG. 2 a longitudinal cross-section of the exemplary embodiment, depicted in a slightly larger scale compared to FIG. 1, in which only the upper device part in the vicinity of the filter housing head is shown, and

FIG. 3 an enlarged representation of the section marked with III in FIG. 2.

The exemplary embodiment of the filter device according to the invention shown in the drawing comprises a filter housing in form of a circular, cylinder-shaped filter bowl 2, of which the figures only depict the section of the upper, open end and which has a closed bowl bottom (not shown). The filter bowl 2 may be closed at the upper end by means of a filter head 4 that forms a kind of end cap, which overlaps with a shirt-like, axially protruding collar 6 an annular body 8 of the housing bowl 2. The annular body 8 forms a radial projection on the filter bowl 2. To facilitate the attachment of the filter head 4 to the filter bowl 2, a thread 10 is formed between the collar 6 of the filter head 4 and the annular body 8 of filter bowl 2. A fluid inlet 12, arranged coaxial to the cylinder axis, is disposed at the upper end of the filter head 4 for the supply of unfiltrate, and a fluid outlet 14 is provided, radially offset, for the filtrate discharge.

The filter element 16, which may be inserted into the filter bowl 2, comprises a hollow, cylinder-shaped filter medium 18 that is bounded at each end by an end cap, as is usual with filter elements of this kind, of which the drawings only show the upper end cap 22 that is assigned to the filter head 4. For the purpose of forming a connection point through which the filter element 16 can be connected to the fluid inlet 12, the end cap 22 is provided with a coaxial, cylindrical extension 24, which forms the fluid passage from the filter head 4 that is attached to filter bowl 2 from the fluid inlet 12 to the internal filter cavity 26, which is surrounded by the filter medium 18. From the filter cavity 26, which forms the unfiltrate chamber in operation, the fluid flows, after flowing through the filter medium 18, into the filtrate chamber 20 located on the outside of said filter cavity 26, and from there to the fluid outlet 14 of the filter head.

To provide a sealed connection between the extension 24 of the end cap 22, which forms the connection point, and the fluid inlet 12, the filter head 4 is provided with a cylindrical connector 28, which cups the edge 30 of the extension 24 of the filter head 4 that is attached to filter bowl 2. A first support point is provided between said edge 30 and the connector 28 in form of a floating bearing 32 to support the filter element 16. This bearing is called a “floating bearing” because this support point provides support in horizontal, radial direction but has no support surfaces that act in the vertical, axial direction. To describe it more accurately, the floating bearing 32 comprises a circumferential groove 34 in the vicinity of the top edge 30 of the extension 24 of the end cap 32, where a sealing ring 36 is radially compressed between the base of the groove 34 and the inside of the cylindrical connector 28 of the filter head 4. The floating bearing 32 thus forms via the sealing ring 36 not only the sealing function of the filter element 16 but also provides support in horizontal direction.

The filter element 16 is supported on filter head 4, which is attached to the filter housing head, via a second support point in form of a second floating bearing 38. Like the first floating bearing 32, the second bearing comprises a sealing ring 40 as bearing component, so that the bearing 38 simultaneously provides a sealing function. The bearing point that comprises the sealing ring 40 is here called a “floating bearing” because, when the filter head 4 is attached to the filter bowl 2, that is, when screwing the filter head 4 tight, the sealing ring 40 is compressed in vertical direction only by the weight of the filter element 16 between a first support surface 42, which is provided on the end cap 22, and a second support surface 44. The first support surface 42 is located on an external circumference ring 46, which surrounds the main part of the end cap 22 as a closed annual body at a radial distance and is attached to the main part via radially extending connecting webs 48. To facilitate the vertical, axial compressing of the sealing ring 40, the circumference ring 46 is provided with a shoulder 50 in form of a radially protruding annular rib that forms the first support surface 42, which compresses the sealing ring 40 against the further support surface 44 through the weight of the filter element 16. The further support surface 44 is located on an annular rib 54 that protrudes radially from the filter housing bowl 2. Due to the axial compression the sealing ring 40 is widened in radial direction and thus forms not only a seal but also a support, which seals in radial direction between filter housing bowl 2 and filter housing head 4. In other words, this forms a seal of the filtrate chamber 20 towards the outside of the filter housing.

Due to the fact that two support points are disposed at an axial distance from each other, which form the two floating bearings 32, 38 and enable relative movements in axial direction, and because floating bearing 32 as well as floating bearing 38 comprise, as support element, an elastomeric sealing ring 36 and 40 respectively, the support means as a whole has an overall vibration damping effect and provides for a reliable operation of the filter element 16 when vibration loads occur in operation. Because the filter element 16 may move axially, counter to the force of the weight, the internal boundary surface 56 of the connector 28 of the head 4, which adjoins fluid inlet 12, forms an end-stop surface for the rim 30 of the extension 24 of the end cap 22. Axial movements are thus limited to an amount at which the circumferential ring 46 of the end cap 22 still remains in a position in which it cups the rim 58 of the filter bowl 2. As a result of the floating bearings, the filter element is supported in the filter housing in a “floating” manner and is able to adjust itself correspondingly in vertical orientation when the entire filter device is installed in a normal position; in particular during filtration it will find its own sealing position due to the fluid pressure. 

1. A filter device comprising a filter housing (2, 4) that retains a filter element (16), which separates inside the filter housing (2, 4) an unfiltrate chamber (26) from a filtrate chamber (20), in which the filter element (16) is sealed off from the filter housing (2, 4) by means of a sealing device (36, 40), characterised in that the filter element (16) is supported inside the filter housing (2, 4) solely by floating bearings (32, 38).
 2. The filter device according to claim 1, characterised in that the bearings (32, 38) act primarily in vertical direction with respect to each other, and that a first floating bearing (32) acts primarily in horizontal, radial direction when the device is in operation, and a second floating bearing (38) acts in vertical, axial direction.
 3. The filter device according to claim 1, characterised in that the respective bearing (32, 38) comprises a sealing ring (36, 40) of the sealing device.
 4. The filter device according to claim 1, characterised in that the respective sealing ring (36, 40), which co-forms the bearing (32, 38), is elastically flexible and consists preferably of an elastomeric material.
 5. The filter device according to claim 1, characterised in that the sealing ring (36), which co-forms the first floating bearing (32), is arranged between a connection point (24) of the filter element (16) and a head (4) of the filter housing (2, 4) and that the sealing ring (40), which co-forms the second floating bearing (38), is arranged between the said filter head (4) and a filter bowl (2) of the filter housing (2, 4).
 6. Filter device according to claim 1, characterised in that the one end cap (22) of the filter element (16), which forms the connection point (24), is provided with a support surface (42) that overlaps the filter bowl (2), where said support surface (42) compresses with increasing connection between filter head (4) and filter bowl (2) the bearing-sealing ring (40), which acts primarily in vertical direction, against a further support surface (44) in such a way that said sealing ring (40) widens in radial direction.
 7. The filter device according to claim 1, characterised in that the further support surface (44) for the bearing-sealing ring (40) that forms the second floating bearing (38) is part of the filter bowl (2).
 8. The filter device according to claim 1, characterised in that the one support surface (42) forms a closed external circumference ring (46), which is attached via connecting webs (48) to the other parts of the end cap (22) and which is provided with a shoulder (50) at the outer circumference above the second floating bearing (38).
 9. The filter device according to claim 1, characterised in that the sealing ring (36) that forms part of the first floating bearing (32) may be located in a circumferential groove (34) of a cylindrical extension (24) of the end cap (22), which delimits the connection point so that the sealing ring (36) may be brought in contact with a cylindrical connection part (28) of the filter head (4).
 10. The filter device according to claim 1, characterised in that the diameter of the sealing ring (36) that co-forms the first floating bearing (32) is smaller than the diameter of the sealing ring (40) that co-forms the second floating bearing (38), and that both bearings (32, 38) are located at a distance from each other in axial direction so that the filter element (16) is supported essentially free of vibrations inside the filter housing (2, 4).
 11. A filter element (16), in particular for application in a filter device according to claim 1, comprising a filter material (18) that extends between two end caps (22), characterised in that at least one of the end caps (22) of the filter element (16) is provided with receptacles for the components (36, 40) of two bearings (32, 38), the working direction of which extends essentially vertical to each other.
 12. The filter element according to claim 11, characterised in that the respective bearing (32, 38) is co-formed by a sealing ring (36, 40) of a sealing device. 